netdev - Re: [PATCH net 2/2] bnx2x: fix napi poll return value for repoll

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Date:	Tue, 20 Jan 2015 20:54:29 +0530 (IST)
From:	Govindarajulu Varadarajan <_govind@....com>
To:	Eric Dumazet <eric.dumazet@...il.com>
cc:	Govindarajulu Varadarajan <_govind@....com>,
	Willem de Bruijn <willemb@...gle.com>, davem@...emloft.net,
	netdev@...r.kernel.org, ariel.elior@...gic.com, ssujith@...co.com,
	benve@...co.com
Subject: Re: [PATCH net 2/2] bnx2x: fix napi poll return value for repoll

On Tue, 20 Jan 2015, Eric Dumazet wrote:

> On Tue, 2015-01-20 at 18:46 +0530, Govindarajulu Varadarajan wrote:
>> With the commit d75b1ade567ffab ("net: less interrupt masking in NAPI") napi repoll
>> is done only when work_done == budget. When in busy_poll is we return 0 in
>> napi_poll. We should return budget. Also do not return workdone > budget.
>>
>
> I am not sure.
>

This is based on f41281d02f8b94e136f78cb1b6a5d78182c222bd &
9dfa9a27b620640322588df399eb8f624b48d877

I do not know about bnx2x, but in enic driver, when busy_poll is enables
rq clean is not happening. This is because, in napi_poll() when
work_done < budget, we do not repoll. At this point, enic has disables rq intr
and has not called napi_complete. Driver assumes that napi will repoll.
Which does not happen.

Lot of drivers I have checked return full budget if they want to repoll.
eg. mlx4_en_poll_rx_cq()

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